Johnny Walker is asked by the President to save Howard Hughes and Locate and explore the fabled city of Atlantis in the novel, The Search For Atlantis *.

When
Howard Hughes is kidnaped, the CIA brings an American revered CIA agent out of
retirement to track him down. The elderly Hughes is on a Russian ice cutter
exploring Antarctica in search of Atlantis where a new theory states it is
buried under tons of ice. The Kidnapers are demanding an unthinkably huge
ransom, but though the CIA can’t pay the full amount, they fear that if the
Russian Red Army should capture Hughes, under torture he might reveal their
espionage secrets. When Hughes is finally freed, and the kidnappers are
thwarted, the U.S. President asks the enterprising agent to take over the
search for the fabled city on a new ship he orders made available for the icy trek.
The City is found mostly intact, but an underground volcano suddenly erupts
halting further exploration and forcing a mandatory ship retreat amid fires.